We propose to develop a quantitative model of the biomechanical basis of mild traumatic brain injury (MTBI) for a pediatric population. This expands upon our initial five year Bioengineering Research Partnership (BRP) in which we developed a biomechanical model of MTBI for a collegiate population, which has resulted in a database of more than 500,000 recorded head impacts in collegiate sports. This work has produced substantial advancements in the knowledge of injury mechanisms and head impact exposure, and resulted in translational outcomes, including: 1) adult brain injury criteria that provide improved diagnosis strategies and prevention systems, 2) optimized helmet design criteria and publically available helmet evaluations that have improved helmet technologies, and 3) football practice guidelines that have reduced head impact exposure in collegiate football. The proposed pediatric MTBI model will enable translational research and the development of new clinical and therapeutic approaches to reduce the incidence and negative effects of MTBI in youth athletes. Experimental and clinical projects among our team members will allow us to test hypotheses specific to the underlying pathomechanics and clinical sequelae of pediatric MTBI. A cohort of 1050 youth football players between the ages of 6 and 14 years will wear instrumented helmets to collect head acceleration data and clinical data over a 5 year period. Athletic environments offer a rich opportunity for collecting data on large numbers of head impacts, which enables research that combines biomechanical head impact data with the subsequent neurobiologic and functional changes in the brain. To date, biomechanical MTBI research has focused primarily on the approximately 100,000 athletes participating in college and professional football in the United States; however, little is known about the 3,500,000 youth (6 years to 14 years) athletes playing football each year. We hypothesize that head acceleration due to impact is predictive of the type and severity of brain injury, and correlates t specific clinical measures of pediatric MTBI. We aim to: 1) Quantify head impact exposure in youth football, 2) Determine head acceleration injury tolerance for sustaining pediatric MTBI, and 3) Correlate head acceleration with clinical variables related to pediatric MTBI. We have performed a pilot study on 119 youth football players aged 7 to 18 years to demonstrate the feasibility of the proposed work. Successful completion of the proposed hypothesis-driven research will result in the development of novel protective equipment strategies, diagnostic tools for field use and other healthcare settings, novel strategies for return to play decisions, and educational tools for disseminating information about the evaluation and prevention of MTBI in the pediatric population. Additionally, our research results will have translational relevance to the general population, including motor vehicle crashes and pediatric consumer products.